1. Field of the Invention
The present invention relates to an electronic circuit for indication of the operation status of a vehicle brake system. More specifically, the present invention relates to an electronic circuit for indication of the operational status of a vehicle brake system where first and second illumination sources are activated and deactivated to indicate the operational status of the braking system.
2. Description of the Prior Art
Prior art brake wear and adjustment systems connect each sensor to a condition electronics module to generate a signal to the driver or mechanic that brake service is required. Many systems have been developed in the past to provide a signal to a vehicle operator to warn that brake lining wear or actuator travel has progressed to a predetermined thickness. However, these systems have been generally unsatisfactory due to their complexity and/or unreliability.
U.S. Pat. Nos. 3,594,721; 3,716,831; 3,735,343; 3,755,774; 3,869,695 and 3,902,157 the disclosures of which are hereby incorporated by reference, disclose electronic signaling systems for the detection and notification of abnormal brake wear. One disadvantage with many of these systems is the parallel wiring configuration which results in a large number of conductors that must be used to connect the sensors with the electronic monitoring unit. Another disadvantage is that some prior art systems do not indicate when brake service is required if a short to ground fault occurs and in addition, provide a flow of electrical current through the wheel bearing which can result in a decreased bearing service life.
U.S. Pat. No. 3,456,236 discloses a brake shoe wear indicator system where the wear sensors are connected in series to a relay which, when de-energized, closes contacts to light a bulb in a trouble alarm circuit. This concept lacks the reliability required of a brake condition alarm system because it incorrectly indicates that the brake system is operational when the brakes are in fact worn out but the light is burned out or there exists an open circuit to the bulb. Thus, the condition of the brakes cannot be reliably ascertained using this type of prior art system.